1. Field of the Invention
This invention generally relates to diamond bonded materials and constructions, more specifically, diamond bonded materials and constructions comprising a silicon containing region and compacts/constructions formed therefrom that are engineered to provide desired properties of improved thermal stability and fracture toughness when compared to conventional polycrystalline diamond materials.
2. Background of the Invention
Polycrystalline diamond (PCD) materials and PCD elements formed therefrom are well known in the art. Conventional PCD is formed by combining a volume of diamond powder and subjecting the same extremely high pressure-high temperature (HPHT) process conditions in the presence of a suitable catalyst material, wherein the catalyst material promotes desired intercrystalline diamond-to-diamond bonding between the diamond grains, thereby forming a sintered PCD structure. The resulting PCD structure produces enhanced properties of wear resistance and hardness, making PCD materials extremely useful in aggressive wear and cutting applications where high levels of wear resistance and hardness are desired.
Catalyst materials that are typically used for forming conventional PCD include metals from Group VIII of the CAS version of the Periodic table taken from the CRC Handbook of Chemistry and Physics, with cobalt (Co) being the most common. Conventional PCD may comprise from 85 to 95% by volume diamond and a remaining amount of catalyst material. The sintered PCD has a material microstructure comprising a matrix phase of intercrystalline bonded diamond with a plurality of interstitial regions dispersed within the matrix. The catalyst material is present in the microstructure of the PCD material within interstitial regions.
A problem known to exist with such conventional PCD materials is thermal degradation due to differential thermal expansion characteristics between the interstitial catalyst material and the intercrystalline bonded diamond. Such differential thermal expansion is known to occur at temperatures of about 400° C., causing ruptures to occur in the diamond-to-diamond bonding, and resulting in the formation of cracks and chips in the PCD structure.
Another problem known to exist with conventional PCD materials is also related to the presence of the catalyst material in the interstitial regions and the adherence of the catalyst to the diamond crystals to cause another form of thermal degradation. Specifically, the catalyst material is known to cause an undesired catalyzed phase transformation in diamond (converting it to carbon monoxide, carbon dioxide, or graphite) with increasing temperature, thereby limiting practical use of the PCD material to about 750° C.
Attempts at addressing such unwanted forms of thermal degradation in PCD are known in the art. Generally, these attempts have involved the formation of a PCD body having an improved degree of thermal stability when compared to the conventional PCD material discussed above. One known technique of producing a thermally stable PCD body involves at least a two-stage process of first forming a conventional sintered PCD body, by combining diamond grains and a cobalt catalyst material and subjecting the same to HPHT, and then removing the catalyst material therefrom.
This method, which is fairly time consuming, produces a resulting PCD body that is substantially free of the solvent catalyst material, and is therefore promoted as providing a PCD body having improved thermal stability. However, the resulting thermally stable PCD body, or thermally stable polycrystalline diamond (TSP) typically does not include a metallic substrate attached thereto by catalyst infiltration from such metallic substrate due to the catalyst removal process. Such TSP body also has a coefficient of thermal expansion that is sufficiently different from that of conventional metallic substrate materials (such as WC—Co and the like) that are typically infiltrated or otherwise attached to the PCD body to provide a PCD compact that adapts the PCD body for use in many desirable applications. This difference in thermal expansion between the thermally stable PCD body and the metallic substrate, and the poor wetability of the thermally stable PCD body diamond surface makes it very difficult to bond the thermally stable PCD body to conventionally used metallic substrates, thereby requiring that the PCD body itself be attached or mounted directly to a device for use.
However, since such conventional thermally stable PCD body is devoid of a metallic substrate, it cannot (e.g., when configured for use as a drill bit cutter) be attached to a drill bit by conventional brazing process. The use of such TSP body in this particular application necessitates that the PCD body itself be mounted to the drill bit by mechanical or interference fit during manufacturing of the drill bit, which is labor intensive, time consuming, and which does not provide a most secure method of attachment.
Additionally, because such conventional thermally stable PCD body no longer includes the catalyst material, it is known to be relatively brittle and have poor impact strength and toughness, thereby limiting its use to less extreme or severe applications and making such TSP bodies generally unsuited for use in aggressive applications such as subterranean drilling and the like.
It is, therefore, desired that a diamond bonded construction be developed that has improved properties of thermal stability when compared to conventional PCD materials. It is also desired that a diamond compact be developed that includes a thermally stable diamond material bonded to a suitable metallic substrate to facilitate attachment of the compact to an application device by conventional method such as welding or brazing and the like. It is further desired that such thermally stable diamond material and compact formed therefrom have improved properties of hardness/toughness without sacrificing desired properties of impact strength and fracture toughness when compared to the conventional TSP material described above. It is further desired that such a product may be manufactured at reasonable cost without requiring excessive manufacturing times and without the use of exotic materials or techniques.